High voltage power transmission lines carrying voltages in the hundreds of kilowatt range have been constructed to extend from spaced towers or poles in terrain which is often practically inaccessible to land vehicles. In recent years, a number of methods and devices have been developed to facilitate the repair and maintenance of high voltage power transmission lines which are accessed by helicopter.
Lattice-type towers are employed for supporting multiple high voltage electrical conductors. The conductors are typically supported under the arms or bridges of such towers using a pair of suspension insulators per conductor. Periodically, it is necessary to replace the insulators because they are visibly damaged or as part of a general maintenance plan. Typically, insulators are attached via pins to the towers and via pins to a yoke plate which supports the conductor. These pins must be manually removed by linemen placed on the tower via helicopter in order to replace the insulators. Damaged or worn insulators are removed from the tower via helicopter and replacement insulators are delivered to the tower via helicopter. It will be appreciated that high voltage electrical insulators are extremely heavy, e.g., about 200 pounds, and their weight makes them too difficult to be safely handled by linemen on the tower, particularly when it is appreciated that these linemen are standing on narrow girders. Thus, the aid of a helicopter is required. Unfortunately, a helicopter does not have access to the undersides of the tower bridge or tower arms from which the insulators are supported, making it difficult to work with the helicopter without the linemen physically dragging each damaged and replacement insulator along the tower to or from a location which the helicopter can access.
Accordingly, there exists a need for a transport device for moving damaged and replacement insulators along a lattice-type tower which may be safely emplaced on a tower via helicopter, which is light enough to be handled by a lineman on a tower, which is strong enough to support a heavy electrical insulator, which will be stable on a structure such as a lattice-type tower and which includes insulator support means for safely cradling an electrical insulator during movement along the tower and during transport to and from the tower via helicopter.